This invention belongs to the broad realm of production engineering or production management and deals more specifically with a novel method of automatically ascertaining the working state of a machine or apparatus with a view to higher production efficiency per unit time. The invention is also specifically directed to means for use with the inventive method.
The method and means according to the invention have been developed for, and actually find optimum application to, printing presses; nevertheless, they lend themselves to ready adaptation for a variety of other machines or apparatus such as, for example, electronic platemaking machines and bookbinding machines. With this adaptability understood, the invention will be disclosed herein only in association with printing presses.
Any machine has downtime. A knowledge of its exact lengths and causes is a prerequisite for the development of effective remedies and hence for an increase in the production of the machine per unit time. In the printing industry, for example, a pressman in charge of each printing press has heretofore made it his duty to fill in a form, called a presswork sheet (shown in FIG. 1 of the attached drawings), with pertinent data representative of the working condition of the press. The data during each given period of time are compiled and put to analytical study of the working state of the printing press.
Given below by way of example is a list of items to be checked upon by the pressman in filling in the presswork sheet:
I. Volume of production (the number of printed sheets or rolls) PA0 II. Production time (the time during which the printing press is scheduled to be, but actually may or may not be, in operation).
A. Operation time (the time during which the press is in normal printing operation). PA1 B. Downtime (lost production time).
1. Preparation time PA2 2. Interruption time.
a. Conversion of printing plates or cylinders. PA3 b. Other causes. PA3 a. Upkeep of the printing plate or cylinder. PA3 b. Repairs of the press. PA3 c. Other causes.
The "other causes" for "preparation time", one of the two divisions of "downtime", may include such a diversity of preparatory operations as the changing of dampening rollers, inking rollers, blankets, etc., and the washing of the blanket cylinder, inking rollers, etc. The "other causes" for "interruption time", the other division of "downtime", may include such incidental impediments as the out-of-stock of printing paper, the non-arrival of data or other material to be printed, and cleaning. Further, the "upkeep of the printing plate or cylinder", classified as one of the causes for "interruption time", may be subdivided into the removal of smudges or smears, the repair of damage, etc. Each of the other listed items likewise resolves itself into a plurality of factors.
It is therefore no easy task for a pressman to check on all these items and record the required data on the presswork sheet. (A manner of filling in the presswork sheet will be detailed later with reference to FIG. 1.) He may fail to record all the required data or may record inaccurately, making impossible the proper assessment of the working state of the printing press.
As additional duty hitherto imposed on the pressman has been to calculate the lengths of the above enumerated division and subdivisions of "production time", during each preassigned length of such time, and to record the results on the presswork sheet. This practice is also objectionable in view of unavoidable miscalculations and the possible failure by the pressman to fill in all the necessary blanks.